Heretofore, for example, when structural components of an automobile or the like are welded together, a clamp apparatus is used for clamping such structural components in place.
Such a clamp apparatus includes a main body and a clamp arm that is rotatable through a predetermined angle via a toggle link mechanism disposed inside the main body. Additionally, the clamp arm is rotated at the predetermined angle through the toggle link mechanism, which is connected to a rod arranged inside the main body, and by displacement of the rod along the axial direction, so that corresponding to the direction of rotation, the clamp arm is switched between a clamped state capable of clamping the workpiece and an unclamped state in which the clamped state of the workpiece is released.
For example, as disclosed in the specification of German Patent Publication No. DE 196 45 778 A1, an air-driven system is known, in which a piston disposed inside a main body is displaceable under the supply of a pressure fluid. Upon displacement of the piston, a clamp arm is rotated through a toggle link mechanism connected to a piston rod for switching between clamped and unclamped states of the workpiece. Also, a hand operated system is known, which comprises a handle that is operable by an operator and is capable of switching between clamped and unclamped states of the workpiece with the clamp arm by rotating the handle.
Incidentally, in the case that the aforementioned air-driven or manually driven clamp apparatus is used, respective clamp apparatuses are prepared separately depending on the use environment, for carrying out operations to clamp workpieces. However, in this case, an air-driven clamp apparatus and a manually driven clamp apparatus must be provided separately and respectively, such that the preparatory procedures therefore are complicated, together with concerns over increasing equipment costs.